Chairs may have a pair of opposing chair arms and arm rests in order to provide increased comfort and to decrease fatigue by providing support for the user's arms and lateral support for the body. In some instances, it may be desirable to adjust the width between the arm rests to accommodate different sizes and/or positions of users. However, typical arm rests are rigidly attached to their respective chair arms so that the chair arms must also be adjusted in order to adjust the arm rests. Other arm rests which are adjustable relative to their chair arms use relatively complex mechanisms requiring tools to assemble and disassemble so that it is difficult for the typical user to adjust the width between the arm rests, and the assembly and manufacturing costs are increased.